The present invention relates to endoscopes and particularly to endoscopes fitted with a device for measuring the distance between the subject and the objective or objective lens of the optical system of the endoscope.
In the field of endoscopy the demand is made more and more frequently to determine the distance of human organs or technical parts to be examined from the objective of the endoscope, and the dimensions of a subject. For this purpose use has been made already of measuring rods to be passed through the shaft of the endoscope which are advanced toward the subject during observation, during which process the distance of the subject from the objective can be read off on a proximal graduation on the measuring rods. With this method, however, it is not possible to measure distance accurately, apart from the fact that manipulation of the instrument is made more difficult for the doctor and a burden is placed on the patient.
For this reason it is an object of the invention to dispense with such measuring rods for measuring distances between subject and objective of the optical system of the endoscope, and to enable the doctor to perform the measurement directly during the objservation or examination of the subject without coming into contact with it.